T avery



Aug. 17, 1948.

H. T. AVERY KEYBOARD CLEARING MECHANISM 5 Sheets-Sheet 1 Filed June 12, 1945 INVENTOR Hare/0 T Avery n m m uwfmn 7? AT'F O RNEYS Aug. 17, 1948. H. T. AVERY KEYBOARD CLEARING MECHANISM 5 Sheets-Sheet 2 Filed June 12, 1945 INVENTOR fiaro/o TAV'e/fy Aug 17, 1948. H. T. AVERY 2,447,108

KEYBOARD CLEARING MECHANISM Filed June 12, 1945 5 sheec et 3 O l/ a D b r (a K E. Ea.

w k? I\ v Q I? & I:

ATTORNEYS Aug. -17, 1948. H. T. AVERY KEYBOARD CLEARING MECHANISM Filed June 12, 1945 5 Sheets-Sheet 4 INVENTOR Hora/0 Z'Az e/"y A'TTORNEYS H. Ti AVERY KEYBOARD CLEARING MECHANISM Aug. 17, 1948.

5 SheetsSheet 5 Filed June 12, 1945 ayg FllE |51 (own/er f/earke a A c/ua f0)" FLLE E ATTORNEYS Patented Aug. 17, 1948 UNITED STATES PATENT FFICE KEYBOARD CLEARING MECHANISBE Application June 12, 1945, Serial No. 599,087

2 Claims. (Cl. 235-79) The present invention relates to calculating machines of the type capable of performing problems in addition, subtraction, multiplication and division and more particularly to machines having what is known as a full or multiple column keyboard, a keyboard clearing mechanism and an add key, the latter being effective, upon depression thereof, to enable the clearing mechanism to automatically release the depressed numeral keys during each cycle of operation of the machine. The add key may also be effective to limit the machine to one cycle of operation for each depression of the plus or minus bar regardless of the length of time during which the bar say be held depressed.

In machines of this character the add key may be held mechanically in depressed position throughout a series of additions or subtractions so that after the entry of each acldend or subtrahend into the accumulator register the keyboard is automatically cleared, and the operator need only to set up and initiate entry of one item after another. However, in performing problems of division on this type of machine the procedure comprises the repeated subtraction of the divisor set up on the keyboard from the dividend or remainder, espectively, which stands in the accumulator register, and in performing divisions it is therefore necessary that the keyboard shall not be cleared during each subtractive operation for which reason the add key has to be released. For this purpose machines of the type referred to, and which have a special division lever or key for initiating automatic or semi-automatic division operation, may be provided with mechanism such as that shown in my Patent 2,256,799 whereby movement of the division lever or key into the division initiating position operates levers linked thereto which are effective to release the add key, thus making it unnecessary for the operator to manually release said key when changin from calculations of addition or subtraction to a division operation,

In certain instances, however, it may not be desirable to link additional mechanism adapted to effect release of the add key to the division key or lever of a calculating machine lest the o erational load of the division key or lever become too high due to the added leverage required to release the add key. Then it may also be desirable to have automatic add-key-release upon initiation of calculations of division in machines that do not have a special division key or division mechanism and wherein a division-key-operated release mechanism of the type shown in my above mentioned patent is therefore not feasible.

It is an object of the present invention to provide improved means for automatically releasing the add key in calculatin machines when initiating calculations of division.

More specifically it is an object of the present invention to provide means in calculating machines by which the add key is automatically released when changing from calculations of addition or subtraction to calculations of division without burdening a division key, that may or not be provided in the machine, with any special add-key-rele'ase linkage.

The present invention is based on the observation that in performing calculations of division the dividend is first entered into the accumulator register which causes the counter register to indicate the value of l, which value must be cleared out before the division calculation is begun in order that a true quotient may appear in the counter register; it is also based on the fact that in divisions the first operation of the actuator driving mechanism immediately following such clearance of the counter register is always a subtractive one. According to the present invention, therefore, sequential operation of the counter clearance mechanism and of the actuator driving mechanism in a subtractive direction is arranged to bring about release of the add key.

t is a particular object of the present inventic-n to provide normally ineffective releasemechanism for the add-key adapted to be placed into effective condition by operation of the counter register clearance mechanism and, thus conditioned, to become effective to release the add key only by an immediately subsequent operation of the actuator driving mechanism i a subtractive direction with no additive operation intervening.

It is an additional object of the present invention to provide a normally ineffective add-key release-mechanism of the type referred to which when placed into effective condition is adapted to be restored to its normal condition during operation of the actuator drivin mechanism.

It is still another object of the present invention to provide a normally ineffective add-key release-mechanism of the type referred to which, when placed into eifective condition, is adapted to be restored to its ineffective condition without effecting release of the add key, by immediately subsequent operation of the actuator driving mechanism in additive direction.

Other objects will appear from the following description of a preferred form of the invention, reference being had to the accompanying drawings in which:

Figure l is a longitudinal section as viewed from the right of the machine, illustrating the add-key releasing-mechanism and part of the drive mechanism.

Figure 2 is a detail view in section showing the counter-clearance drive-mechanism and the control therefor.

Figure 3 is a fragmentary longitudinal section as viewed from the right illustrating the mechanism for conditioning the add-key release-mechanism.

Figure 4 is a detail view looking at the rear of the machine and partly in cross-section showing the driving and reversing mechanism.

Figure 5 is a fragmentary detail view of part of the mechanism shown in Figure 4.

Figure 6 is a section, as viewed from the left of the machine, showing the drive and drive control mechanisms.

Figure 7 is a .section as viewed from the right showing the 'plus and minus bars and the mechanism controlled thereby for reversing the drive to the actuator.

Figure 8 is a diagrammatic view :of the gear trains for the clearing mechanisms of the accumulator-register and the counter register.

Figure 9 is a diagrammatic view of "the gear trains for driving the accumulator and counter actuators.

The invention has been illustrated as adapted to calculating machines of the reversible rotary actuator type disclosed in the patents referred to hereinafter to which reference is hereby made fora full disclosure of details not particularly illustrated or described herein. It is to be understood, however, that the invention is not limited to the particular type of machine disclosed in the said patents in which the direction of operation of the actuators is controlled by a plus oriminus bar or by a division initiating key, but

it may also be embodied in a machine in which the direction of operation of the actuators is determined by the direction of rotation of a hand crank.

Keyboard Calculating machines of the type illustrated such as that .shown in the Friden Reissue Patent Number 18,911 include a numeral keyboard comprising a plurality of ordinal rows of keys each row including keys numbered 1 to 9 by depression of which factors .are entered into the machine.

Key latching means is provided for each row of keys and is effective upon depression of a key to latch that 'key in depressed position until such a time as the key may be released by the disabling of said latching means.

In Figure 1 there is illustrated "a single row of such keys. Each key 5 comprises a key stem Ill which is suitably mounted in the frame of the machine and is normally maintained in raised Mounted on the lower pression of any one of the numeral keys 5 the lug l2 moves the slide l3 rcarwardly against the pressure of the spring l6, and after the lug passes beneath the slide it, the slide is moved to its normal forward position by spring it, thereby securely looking the key in depressed position.

The -:calculating machine in connection with which the present invention is illustrated, comprises a reversible rotary actuator l8 (Figures 3 and 4) which, upon depression of the numeral keys .5, receives the setting which corresponds to the value indicated upon said keys, the way ,in which theikeys eflect the setting of the actuator :being disclosed in the Friden Patent Number 1,524,924. Rotation of the actuator transfers thisv-alue to the numeral wheels 59 of the accumulator register 23. When the actuator i8 is rotated in one direction the value introduced therein is added to the value standing in the accumulator register and when the actuator is rotated in the opposite direction the value introducedtherein is subtracted from the value standing insa'id accumulator register.

The machine is also provided with a counter register comprising numeral wheels 23 (Figure 1) and a counter actuatorcomprising a one tooth gear .or counter finger H!) which is keyed to, and .slidable longitudinally on a shaft M9 by means .of a flanged .collar I28. The shaft H9 is driven in time with the accumulator, and the .collar 12B and finger H8 are slid on the shaft byaforked member Ht which is coupled to the carriage of the accumulator Ell in a manner shown in the 'Friden Patent Number 2,028,540, so that as the carriage is shifted ordinally, the counter finger H8 is also shifted in unison therewith but in opposite direction to enable it to actuate the proper denominational orders of the counter register.

Motor drive mechanism Mot'ordrive means is provided for driving the accumulator actuator is and the actuating finger 1 1'8. It includes appropriate gearing which is adapted to flee reversibly connected to the actuators to drive the same in either of two directions.

Referring to the drawings, the driving means for the accumulator and counter actuators includes an electric motor 2-65 (Figures 8 and 9) having a pinion 39 mounted on the shaft 260, thereof which meshes with a gear 3!. Gear 32 rotates a gear 32 which meshes with a gear 33 fixed on a drive shaft 54. A clutch 36 is included in the drive train, the driving member of which is a ratchet 31 (Figure 6) fixed to and driven by drive shaft 34, so that whenever the motor is energized the ratchet 37 rotates constantly in a counter-clockwise direction as viewed in Figure 6. Enclosing the ratchet 3? is a cylindrical housing 38 which constitutes the driven member of the clutch A clutch driving pawl s! is pivoted on a stud 40 carried by the housing 35, and is urged into driving engagement with the ratchet 31 by :means of a small compression spring 52, which is disposed within a spring socket provided in the pawl 41 .and is compressed between the pawl 41 and housing 33,. When the clutch to is disengaged the pawl M is held out of driving relationship with the ratchet 3'! by means of a clutch control mechanism comprising control dog d3 journaled on a stub shaft M, supported in the machine frame. The left or backward arm of the clutch dog has integral therewith a nose 51, adapted to project through an appropriately positioned aperture in the clutch housing 38 when the clutch is in full cycle position, so as to engage the tail of the pawl 4| and thus hold the pawl M in clutch-disengaging position. The clutch dog 43 is urged to the clutch disengaging position shown in Figure 6 by a spring 48 tensioned between a right or forward arm of clutch dog 3 and a stud it on the base of the machine. Rocking of the clutch dog in a counter-clockwise direction to clutch engaging position, upon depression of either of a pair of control keys described later, removes the nose 41 from the clutch housing and permits the spring 42 to rock the pawl 4| into engagement with the ratchet ill, thereby eifecting a driving connection between the driving and driven parts of the clutch.

Plus and minus bars Means are provided to rock the clutch dog 43 to clutch engaging position for the desired number of revolutions to perform a selected calculation. A laterally projecting pin 5i (Figure 6), mounted on the forward arm of the clutch dog 43, normally lies within a notch 52 formed in the rear end of a control link. 53. The forward end of the control link is pivoted at 54 to the forward arm of a bell crank 51, pivoted at 53 to a vertical support plate 59 forming part of the frame of the machine.

A plus bar 63 and a minus bar '52 (Figures 6 and 7) are so arranged that depression of either causes engagement of the clutch 35 described above. The plus bar 63 is carried by a two-armed frame 64 pivotally connected at opposite ends to the ends of two parallel bell levers 3 and 8'5, each pivoted to the machine frame by studs 68 and E9, respectively, which are disposed below and to the left of the respective connections of the levers and the plus bar frame 54 as viewed in Figure '7. A spring H3 is tensioned between the lower arm of bell lever 65 and a stud lea mounted in the machine frame to the right of said arm, so as to maintain the plus bar in raised position. A roller H (Figures '7 and 6) is rotatably mounted on plus bar frame 84 and lies against the forward edge of bell crank 51 (Figure 6). Due to the position of studs 88 and 69 (Figure '7) with respect to the pivotal connections of levers E5 and 67 with the plus bar frame 6s, depression of the plus bar will move frame s4 and roller ll downwardly and toward the rear of the machine causing roller ii to rock hell crank 51 counter-clockwise about its pivot as viewed in Figure 6. This moves link 53 rearwardly which, in turn, rocks clutch dog 43 counter-clockwise into the clutch engaging position as described before.

Also the minus bar 12 is adapted to rock the bell crank 57 and cause engagement of the main 'ciutch. For this purpose the arm 62 of bell crank extends obliquely, upwardly and rearwardly and underlies a roller '56 pivoted to the stem of the minus bar 12 so that depression of the latter rocks the arm '52 of hell crank 51 counter-clockto cause a rearward shift of control link 53 and hence engagement of clutch 35. A torsion spring 13 is arranged to raise the minus bar 12 to its initial position when the operator releases bar. When any depr ssed bar has returned to its initial position spring 48 returns clutch dog 43 to the clutch disengaging position shown in Figure 6 and it also returns link 53 and bell crank 51 to their initial positions in cooperation with the spring 5|.

Reverse mechanism for accumulator actuator As described hereinbefore the actuators are driven in one direction during additive or plus calculations and in the opposite direction during subtractive or minus calculations. The main clutch which is provided for driving the actuators is a one-direction clutch, therefore a reverse unit is provided in the drive train between the main clutch and the actuators. The reverse unit is under control of the plus and minus bars such that depression of the plus bar adjusts the reverse unit to its plus setting, if it is not already there, before it causes engagement of the main clutch, whereas depression of the minus bar adjusts the reverse unit to its minus setting.

This reversing mechanism is disclosed in the Friden Patent 1,682,901 to which reference is directed for details not specifically described herein.

Two gears E i and 98 (Figures 4, 7, and 9) are so arranged that one or the other is operatively connected to clutch 36. The mechanism for connecting either gear 91 or gear 98 with the main clutch 36 is shown in section in Figure 4. It includes an axially shiftable shaft HJI which is centrally disposed within a tubular extension of the hub of clutch housing 38 on which are freely mounted gears 8'! and 98. Shaft lBl carries a cross pin 99 which extends through a longitudinal slot in the tubular hub of the clutch housing 38 and depending upon the axial position of shaft iill it also protrudes into a recess in the hub of either gear 9'! 0r gear 98, thus coupling one or the other of the two gears to clutch housing When the pin 99 is in the right end of the slot (as viewed in Figure 4), in the tubular extension of the hub of the clutch housing 38 it couples the latter to the gear 98, whereas when the pin slid toward the left it disconnects the clutch from gear 98 and couples it to gear 81. When gear Bl! is connected to the main clutch 35 the drive is transmitted through a train including gears 3?, H32 and W3, shaft EM, gears I06, ill! and M8, to the accumulator actuator l8 in the direction f the arrows (Figure 9), whereas when gear ii is connected to the main clutch, the drive is transmitted through a train including gears 98 and shaft Hi4, gears 566, I07 and M8 to drive the accumulator actuator [8 in the opposite direction.

The plus and minus bars are arranged to effect the shifting of cross pin 99 in the following manner: Parallel to and slidable with shaft it! is a second shaft 88 rigidly connected to shaft Hi! by link 89 in such a manner that the two shafts slide together as a unit (Figures 3, 4: and 7). Near its right hand end shaft 88 is provided with a vertical slot which is engaged by a bent camming 87a of a reversing lever 8'! (Figure '7). Reversing lever B! is connected to a bell crank 3 through a link 82 all of which are normally held in the positions illustrated in Figure '7 by means of a spring 9|. In this position camming arm his is kept in its clockwise position holding shaft 8-8 and I0! and cross pin 99 (in their left positions (when viewing the machine from the front) and conducting the drive of the motor through gears 88 and IE3 which operates the actuator it in a plus or additive direction.

When the minus bar [2 is depressed, however, a pin T! (Figure 7) which is integral with the bar, engages a substantially horizontal arm 18 of the bell crank 84 and rocks the same counter-clockwise about its pivot l9. This pushes the link 82 backward, or toward the right as viewed in Figure l, rocks-the reversing lever ill coun-ter -clockwise which slides the shaft '38 and ii)! and cross pin toward the right of the machine (or tod left when viewing the machine from rear as shown in Figure 4), conducting the ire through gears e: and tea which operates the actuator is in its minus or subtractive direction.

Upon release of the minus bar, the spring 9l (Figure 7) returns the reverse control mechanism to the plus position shown, but if the plus key is depressed before the spring has time to act,

means are provided to supplement the action of 1 spring 9! and insure the plus setting of the reverse unit before the clutch is again engaged. For this purpose a lever 82 is freely pivoted to the frame of the machine at'93, .one end underlying the roller ll of the plus bar 63 and the other end underlying the arm '58 of the bell crank 8 so that depression of the plus :barrocksthe lever 32 counter-clockwise and forces the bell .crank 34% to theplus positionshown.

Counter driving and reversing mechanism As mentioned briefly hereinbefore, the counter actuator is driven in timed relation with the accumulator actuator, so that the rotations or'cycles of operation of the accumulator actuator are registered in the counter. ,In problems of division, the direction of .rotation of the counter actuator must be reversed with respect to that of the accumulator actuator so that the number of times the divisor is subtracted from the dividend is registered additively in the counter.

This driving and reversing mechanism .for the counter actuator comprises a gear l-LZ (Figure 9) which is splined to the shaft l H of the counter tens-carry drum in such a way that it .is ,slidable lengthwise on the shaft and into mesh with either gear it)?! or a reverse idler gear )2 (Figures .9 and v1) so that the counterand accumulator actuators are driven in the same directions when gear l l2 meshes with gear l.ii2,,and are driven in oppodisclosed in the aforementioned Friden Reissue Patent Number 18,911.

Counter clearing mechanism The operation of the clearing mechanism for the counter register will be briefly set forth in the following description, only those parts of the mechanism operatively associated with the present invention being illustrated in the drawings.

For a full disclosure of the details of construction of this mechanism, reference is directed to the Friden Patent Number 1,858,397 and the Lamb Patent Number 1,935,851.

A zero resetting shaft H6 (Figure 1) extends axially through the numeral wheels 23. Rotation of this shaft through a complete revolution in a clockwise direction serves to return all of the numeral wheels to'zero. It is immaterial for the purpose of the present invention, whether the zero resetting shaft :I l 6 is-rotatedby hand by providing the shaft with acrank .or similar device, or

Suitable means such with the cover plate.

by :power, but in the machine with the aid :of which the present invention is here explained, power operated means are provided for clearing the counter register.

The means for resetting the counter register to zero by power derived from the motor comprises a clear clutch drive shaft I2! (Figures 2 and18) which is driven by the motor through a gear train including gears 59, 3!, 32, 33, shaft .35, gears l22 and i23, and a gear l2li mounted on shaft l2i. Associated with the drive shaft l2l is a clear clutch I25, substantially identical with the main clutch 35 shown and described in connection with Figure 6. The driven side of clutch I26 is connected to the zero resettin shaft H6 (Figures 2 and 8) through a gear train including gears I21, l28 and 529. The gear ratio of the train between the clutch and the shaft M5 is such that for each revolution of the clutch, the shaft I I6 is likewise rotated one revolution.

A clear clutch control dog liiii is pivotally mounted on a shaft i555 (Figure 2) and the left or forward arm thereof is provided with a laterally extending pin Mil which is engaged by the forked end of a lever I45. This lever is pivoted on a stationary shaft l 55 and is normally maintained in the position shown in Figure 2 by a spring I50. A key i5!) is mounted on the end of the lever M5. Depression of key ifiii rocks lever M5 counterclockwise which in turn rocks clutch control dog I30 clockwise to cause engagement of the clear clutch with consequent clearance of the counter register.

Keyboard clearing mechanism In order to set up a new problem on the keyboard of the machine immediately after a calculation in addition or subtraction, it is necessary to "release the previously depressed keys. Although 'this may be performed by manually op- ,erated mechanism provided for tis purpose, it is usually .done by automatic keyboard clearing mechanism which may be selectively enabled or disabled by an add key. When this key is in its raised .position, it disables the clearing mechanism, but when latched down in its depressed position it enables the same to automatically release the numeral keys in response to the cyclic operation of the machine.

The machine embodying the present invention includes an add key 2% (Figure 1), the stem 13! of which is pivoted at 32 to one end of a lever 13%. The lever 533 is pivoted intermediate its ends at H3 3 to the frame of the machine and both the add key 250 and the forward end of the lever I33 are normally held in elevated position by a spring we tensioned between the lower end of the key stem EM and a stud l3? disposed at a higher level in the machine frame. The upper end of the key stem iii-l projects through a slot in the keyboard cover plate, and has a notch 255 which is adapted to engage the cover plate when the key is depressed to retain the in depressed position. For this purpose the pressure of spring l3i6 is diagonally upward towards the rear of the machine-which tends to urge the upper end of the 'key stem forward and the notch into engagement Rearward pressure at the top of thekey by the operator moves the notch 2.5-5 out of engagement with the cover and thus enables the spring l3t to restore the key to its raised position.

The right end of lever hi3 (Figure 1) is bifurcated :and engages a pin I39 laterally projecting from the free end of a pitman MI. The

rear end of the pitman MI is pivotally supported by an eccentric I42 mounted for rotation with the gear I03 in the actuator drive train, so that upon each rotation of the gear I03 the pitman I is reciprocated. The free forward end of the pitman I4! is also provided with an upwardly extending projection I53, which normally stands in the disabled position shown. When the add key 250 is depressed to the position 250a shown by broken lines the lever I33 is rocked counter-clockwise raising its bifurcated end and the forward end of the pitman is moved upwardly to a position in which the projection I43 lies in front of a gate I44 pivoted to the frame of the machine.

Each of the key latching slides I3 described hereinbefore is provided with an upturned ear I46 at its rear end and the arrangement is such that gate I44 is positioned in front of these ears. Hence when the actuator drive train including gear I53 is driven by the main clutch 36 and pitman IdI is reciprocated, its projection I43, when elevated by depression of the add key, engages the gate 144 and rocks it backward thus sliding all the locking slides i3 rearwardly to their key releasin positions from where they may return to normal position under the influence of their restore springs I 6 as further rotation of ear I53 moves pitman MI with its projection M3 into its forward position.

One cycle stop mechanism In machines provided with automatic multiplication mechanism by which the number of rotations of the accumulator actuator may be limited to any desired number between 1 and 9, depending upon the value of what key may have been depressed in a series of nine multiplier keys. depression of the add key may be arranged to enable the plus and minus bars to establish such a setting of the automatic multiplication mechanism as corresponds to that of the unit key of the multiplier keys, so that with the add key in depressed condition, depression of either the plus or minus bar will result in only one cycle of operation of the machine regardless of the duration of time dtu ing which these bars are held depressed. At the same time the add key is arranged to disable, upon depression, the automatic carriage shift that is usually provided in automatic multiplication mechanism so as to prevent undesirable operation of said shift during the performance of multiple additions, the details of such mechanism being described in my above mentioned Patent 2,256,799.

Add key release mechanism As stated in the introduction to this specification division is performed on the machine of the type disclosed herein, and to which the present invention is applicable, by repeatedly subtracting the divisor set up on the keyboard from the dividend or current remainder standing in the accumulator register. Therefore, if the add key is in its depressed position such as might be the condition following an addition or subtraction calculation it is necessary to release the add key before the division calculation may be started.

To avoid the necessity of manually releasing the add key and moreover to avoid the possibility of the operator forgetting to do so, thereby losing the divisor by automatic release of the keyboard during the first division cycle I have provided a novel automatic add key release mechanism which is applicable to calculating machines whether they are of the type in which division is performed under manipulation of the plus and minus bars or by hand crank, and whether they possess a division initiating key or not.

In accordance with my invention I employ a substantially horizontally positioned bar I 41 pivotally supported by two links I48 and I49 which, in turn, are pivoted in the machine frame. The forward end of the bar I4! is provided with a cam face I52 having an oblique and a substantially vertical portion Him and I52b, respectively, and which lies to the rear of, and slightl below, a pin I53 laterally projecting from the lower part of stem 131 of the add key 250.

When the add key 250 is depressed to the position indicated by broken lines, the pin I53 contacts and cams downward along the oblique portion I 52a of the cam face I52 forcing the bar 141 rearwardly until the substantially vertical portion I52b of the cam face I52 lies immediately to the rear of the pin I53 in its depressed position.

Forward movement of the bar I4I will cause the vertical portion I522) of cam I52 to rock pin I53 and hence key 250 clockwise about the pivot I32, thereby releasing the notch 255 from engagement with the cover plate and permitting the spring I36 to return the add key 250 to its inoperative position.

As will be seen from Figure 1 of the drawings, rear link I49 is somewhat longer than the front link I48, and due to this and to the different angular positions of the links when the add key is in its raised condition, the rearward end of bar I41 will rock slightly downward when said bar is moved rearwardly as shown by the dotted line representation of bar I41 and of links H28 and I 49 in Figure 1, which indicates the position of these parts when bar I4! has been pushed rearwardly by depression of the add key 258,

The necessary forward movement to release the add key is imparted to the bar I41 by a horizontal slide I56 (Figure 1) mounted for sliding movement on screws I51 which extend through slots in the slide I56. An extension I58 of slide I56 lies behind the downwardly extending rearward end I59 of the bar I41. The other end of the slide I56- is. disposed in the path of a depending arm IBI' of a bell crank I52 (Figure 3) pivoted at IE3 to an intermediate frame of the machine. Normally a light spring I8! holds arm I5I of bell crank I62 against a stop I86 but when the bell crank IE2 is rocked clockwise against the urgency of this spring I81 the said arm IBI engages the end of the slide I56, if it has previously been displaced rearwardly by depression of the add key, and forces the slide forwardly thereby releasing the add key in the manner heretofore described.

Add key release conditioning mechanism In accordance with my invention I provide automatic mechanism to rock bell crank I62 into its add-key-releasing position and I so arrange matters that this mechanism must first be conditioned for effectiveness by operation of the counter clearance mechanism and, when thus conditioned, can be set into operation only by the accumulator actuator drive train operating in a negative or subtractive direction without any positive or additive operation having intervened. In accordance with my invention I provide additional means to restore the mechanism to its initial ineffective position after it has been operative. Also I so devise the add-key-release mechanism of my invention that when it has been conditioned for eifectiveness, and th next cycle of operation of the accumulator actuator upon an ear I18 on a downwardly extending arm of said cam follower lever III) engages an upwardly extending arm II'l (Figure 3) of a bell crank I13 and rocks the latter clockwise about its pivot Il I against the force of a spring I84. Spring I84 normally'urges arm I'I'I counter-clockwise, as viewed in Figure 3, and arm Ill pressing against ear I18 urges the cam follower lever IIEI (Figure l) clockwise so that when cam I I7 returns to its full cycle position at the end of a clear clutch cycle spring IB i presses nose H3 into the recess Illa of cam II? and returns the parts to the positions shown.

An ear I'II is formed on the other arm I'IZ of the bell crank I73 and normally engages and blocks a nose It'laof an interponent I57! which freely pivoted on a stud I65 carried on a rearwardly extending arm I64 of the bell crank I52 described hereinbefore. A torsion spring I63 urges the interponent IE'I "counter-clockwise about its pivot stud I66 so that when the interponent is released from the restraint of ear I'II it is rocked counter-clockwise by the spring and limited in that direction by a stop ear its formed on the rearward arrn- I'M of bell crank I62.

Operation of the add key release conditioning mechanism The mechanism just described operates in the following manner to put the add key release mechanism into effective condition upon operation of the counter clearance device: When the counter is cleared, rotation of cam I I? moves cam follower lever I Id counter-clockwise which causes bell crank I13 to move clockwise withdrawing its ear III from underneath nose Ifla of interponent IS'I. As a result. thereof interponent IIE'I rocks toward the left, as viewed inFigure 3, under the urgency of spring I I58 and moves its shoulder I33 underneath a stud I82 mounted on the gear I96 which, as described heretofore, is one of the gears in the drive train from the motor to the accumulator actuator, Upon operation of this drive train in a minus direction gear we is driven clockwise, as viewed in Figure 3, causing stud I82 to engage shoulder I83 and to drive the interponent Ifil downwardly. This rocks bell crank I62 clockwise and releases the add key by actuation of the lever and linkage train described under the heading Add key release machanism'.

The location of shoulder I83 on interponent I67 is so chosen that when interponent' It? is unlatched and in its forward position said shoulder I83 lies very closely below actuating stud I82 on gear I06 in its full cycle positionQ Consequently the add key release mechanism is put into operation at the very beginnin of the subtractive cycle which initiates the add key release with the result that rocking projection M3 of pitman [4| is lowered into its idle motion position before rotation of shaft IM and of eccentric M2 to draw it sufiiciently to the rear of th machine to operate the release gate I la of latching slides I31 Thus, in the very cycle which initiates release of the add key a value set up in the keyboard will no longer be released. For the same reason any one-cycle-stop mechanism that may be provided in the machine and which may have been in operation due to depression of the add key,-is disabled at the very beginning of the subtractive cycle initiating release of the add key so that the machine will directly continue to operate uninterruptedly over whatever number of cycles may be necessary to perform the particular division problem, undertaken. v I

Upon operation of the actuator in a plus direc tion, however, gear Iliii moves upwardly or counter-clockwise so that stud I32 will not engage shoulder M3 and interpon'ent IE? will not be actuated. The add key is therefore not released during an additive operation of the machine following operation of the counter clearance device.

Restoring means of the add key release conditiom'ng mechanism Means are also provided to restore the mechanism just described to its initial condition upon operation of the driving mechanism in either plus or minus direction the only difference being that during plus operatio the mechanism is restored without releasing the add key whereas during minus operation the mechanism is restored after the add key has been released.

This restoring means comprises a cam I8l which is mounted for rotation with gear I06. An arm. IQ? of the interponent I 6? (Figures 3 and 5) is formed around the outside and clear of gear IDS into the plane of cam IIII. When the interponent Itl', upon release of its nose IIi'Ia, is rocked counter-clockwise arm I9! comes to rest onthe lower portion of cam I8I. When the cam rotates with gear I it earns the interponent I67 clockwise with the result that the upper edge of the nose Iiiia cams ear ill on the lower arm I'IZ of bell crank I13 upwardly until said nose passes beneath said ear whereupon spring I83 returns the bell crank Ila into the position shown in Figure 3 in which ear I'II engages nose Ifila and blocks return of the interponent I61. The add key release mechanism is thus disabled throughout subsequent actuator cycles in either direction until again conditioned by operation of the counter clearing mechanism.

It should be noted that the mechanism of my invention is such that while it brings about the release of the add key on initiating calculation of division it does not interfere with the advantages offered by the add key mechanism in setting up'th'e dividend and the divisor nor does it interfere with any of the other forms of calculations for which the machine may be employed. Thus, if the operator clears the counter and thereby conditions the add key release mechanism for operation before a dividend'is entered into the accumulator register, the add key release mechanism will not operate during entry of the dividend due to the fact that the direction of operation of the driving mechanism is in a plus or additive direction when the operator introduces the dividend in the accumulator register; this plus operation will restore theadd key release mechanism to ineffective condition and cause operation of the keyboard clearing mechanism for clearing the dividend out of the keyboard preparatory to setting the divisor therein. Also the add key will not be released upon operation of the driving mechanism in a subtractive direction during substraction problems. Operation of the counter clearance mechanism before a subtraction calculation is, of course, eifective to condition the add key release mechanism for operation, but in subtraction calculations it is first necessary to enter the minuend into the accumulator register by a plus operation of the machine which disables the add key release mechanism in the same manner as the setting of a dividend in the accumulator as explained above. Consequently the following minus or subtract operation of the machine for subtracting the subtrahend from the minuend is ineffective to release the add key and is effective to automatically clear the keyboard in the usual way, the difference as against calculations of division being that whereas in calculations of division the result appears in the counter register, in calculations of subtraction the result appears in the accumulator register for which reason it is not necessary to clear the counter register after introducing the minuend into the accumulator register and before commencing operation of the machine in a minus direction which would condition the add key release mechanism for operation and cause release of the add key.

It will be understood that my invention is of particular advantage and applicability to the less expensive types of machine which have no division key or lever and in which the repeated subtractive operations necessary to perform division are effected by holding the minus key depressed for a selected period of time. My invention is equally applicable, however, to hand or motor driven machines having a special division key or lever such as division lever 600 (Fig. 6) which is manually set to initiate division operation; on the machine described in detail in the Avery and Lerch Patent No. 2,014,013 of which the aforementioned Patent No. 2,256,799 is a division. In such machines my invention provides automatic release of the add key on initiating calculations of division without burdening the operation of the division key or lever with additional trains of links and levers.

I claim:

1. In a calculating machine having a keyboard comprising settable numeral keys, means for locking said keys in set position, an accumulator register, a rotary actuator therefor, driving mechanism for rotating said actuator in either of two opposite directions, a counter register and clearing mechanism therefor; the combination of, means operable by said driving mechanism to release the keys from the locking means, said releasing means being adapted to be selectively enabled or disabled, with means operable to disable said key releasing means, a train between said driving mechanism and said disabling means including an element normally in operating position to be actuated by said driving mechanism upon operation of the latter in one direction only to cause the train to operate said disabling means, a latch having a latching position in which it holds said element out of operating position and an unlatching position in which it enables the element to move to said operating position, and means driven by the counter clearing mechanism upon operation thereof to move the latch to said unlatching position,

2. In a calculating machine having a keyboard comprising settable numeral keys, means for locking said keys in set position, an accumulator register, a rotary actuator therefor, reversible driving mechanism operable in either of two opposite directions to rotate said actuator in either a plus or minus direction, a, counter register and clearing mechanism therefor; the combination of, means operable by the driving mechanism to release the keys from the locking means, said releasing means being adapted to be selectively enabled or disabled, with means operable to disable said key releasing means, a train between said driving mechanism and said disabling means including an element normally in operating position to be actuated by said driving mechanism upon operation of the latter in the direction thereof which rotates the actuators in a minus direction only to cause the train to operate said disabling means, a driving member comprising a part of the driving mechanism and effective upon operation of the latter in either of its two opposite directions to move the element out of operating position, a latch having a latching position in which it holds said element out of operating position when moved thereto by said driving member and an unlatching position in which it enables the element to move to operating position, and means driven by the counter clearing mechanism upon operation thereof to move the latch to said unlatching position.

HAROLD T. AVERY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,400,004 Schaller Dec. 13, 1921 2,034,085 Chase Mar. 17, 1936 2,256,799 Avery Sept. 23, 1941 2,260,291 Britten, Jr Oct. 28, 1941 

